Pbocess akd appabattts eob producing nubogeni compounds



A. R. LINDBLAD. PROCESS AND APPARATUS FOR PRODUCING NITROGEN COMPOUNDS, ESPECIALLY NITRIDSI.

APPLICATION FILED MAYI4, I918.

Patented July 29, 1919.

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AXEL RUDOIIF LI'N'DBLAD, 0F STOCEOLM, SWEDEN.

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To all inhom; it may concern:

Be it known that I, Axnr. RUDOLF Lmn- BLAD, subject of the King of Sweden, residin in Hamn atan 1, Stockholm, in the Kingdom of weden, have invented certain new and useful Improvements in Processes and Apparatus for- Producing Nitrogen Compounds, Especially Nitrids, of which the following is a specification.

Amon the compounds of nitrogen with other su stances, the nitrids have long been the object of great interest. Many attempts to produce nitrids on an-industrial scale have in fact been made, but without satisfactory results. The chief reason of this seems to be thatthe peculiar characteristics of these compounds have not been sufliciently observed. A fact which above all must be taken into consideration is that the nitrids are non-fusible; when heated to a very high temperature, they become decomposed before they have yet' melted. Therefore, if continuous workin is to be maintained, arrangements must e made which render it possible to remove from the furnace the resulting product in an unmelted condition. Further, all nitrids requirea high temperature for their formatlon; as a rule about 2000 degrees centigrade, sometimes a slightly lower, but sometimes, on the other hand, a still higher temperature. From this it ensues that satisfactory results can hardly be attained otherwise than with the aid of an electric furnace.

Proceeding from these points of view, the problem, in accordance wlth the present in'- vention, has been solved by heating the charge in an electric furnace and simultaneously injecting nitrogen or nitrogenous gases into the same. T 0 electric current is supplied to the furnace by means of electrodes hanging down into the furnace,'or

introduced throu h openings in the walls of the furnace. hese electrodes enter into the charge in places where the latter forms a free spreading or 'sliding'surface, and are so arranged that thecharge itself forms a greater or lesser part of the resistance'of the circuit. The resulting product is thereu on removed from the furnace, in an unme ted GQMPOUNDS, ESPECIALLY Specification of Letters Intent. Patented July 29, 1919.

Application med May 14, 1918. Serial no. 234,507.

condition, through an opening in the lower 1 part of the. furnace, continuously or at suittion for performing the rocess 1n question. I

Fig. 1 shows an e ectric furnace of ordinary shaft-furnace type, open at the top.

The current is supplied through the electrode 1 which issuspended in the shaft as shown. The other electrode consists of the conductive furnace linin 2. The raw material is charged into t e furnace around the electrode 1, and is heated by the electric current passing throu h it. Nitrogen is blown in through the pipe 3. The'reaction gases thus generated, are allowed to pass out at the top, whereas the resulting nitrid is removed in an unmelted condition through the opening or outlet 4, which is prolonged at its lowerend by the water-cooled ringshaped tube or pi e 5. If continuous removal of the nitrldproduced is desired, this can be effected by arranging a mechanical extraction device, for example a transporting screw, or the like.

surrounded by water-cooled jackets 9 at the point where they pass through the masonry of the furnace. n the bottom of the fur- ;nace is arranged'the discharge opening 10.

Finally there' is a pipe 11 for blowing-in .nitro en through the bottom of the furnace. If it is considered suitable, the shaft may be provided with a closed charging device of suitable construction.

By the use of a furnace as above described all the electrodes required for supplying and leading off the current pass through freesp'aces 15, formed between thecharge and the masonry of the furnace. It is, howis as follows: assuming that the intention is roduce silicon nitrid si N z ilicon dioxid, for example in the form of crushed quartz, together with carbon is charged into the electric furnace and is heated by the action of an electric current. As a result Sit), is reduced to Si, which combines with the nitrogen simultaneously introduced, into nitrid. The reaction may be expressed by the following formula:

The process will be analogous in case of other nitrids, for example aluminium rutrid, magnesium nitrid, boric nitrid, etc.

It is obvious that a number of variations in the process can be made without departing from the principle of the invention, In the form of furnace shown in Fig. 2, the nitrogen or nitrogenous gases can e blown into the pipes 12 and into the free spaces 15. ln furnaces according to Fig, l thefurnace lining obviously need not necessarily be a conductor as has been assumed to be the case in the example given here. The furnace may instead be provided with two or more electrodes hanging down into the furnace. The number of electrodes moreover in both open and closed furnaces, may be varied according to the circumstances,

Having thus described my invention, 1 declare that what I claim is:

1, An electric furnace for producing nitrogen compounds such.as nitrids and the like, comprising a furnace chamber, having an opening for introducing a charge into the same, said chamber being of such a form that a free space exists between certain portions of the chamber and the charge in the chamber, electrodes extending through the wall of the furnace chamber and into the same at places where the charge is not in contact with the chamber, said chamber being formed with an outlet at its lower end, and means for supplying nitrogenous gases to said chamber.

2. An electric furnace comprising a chamber of inverted frusto-conical formation and having an axially disposed inlet at the upper end thereof, electrodes extending into the same chamber between the side walls of the chamber and the outlet, and means for supplying nitrogenous gases to said cham- 3. Process for producing nitrid comprising the charging of the raw material into an electrical furnace and there heating the same by means of electric current supplied and carried ofl' through an electrode or arness where this has a free surface, nitrogen or nitrogenous gases being simultaneously introduced into the lower part of the furnace chamber, and the resulting product being removed from the furnace in an unmelted condition through openings in the lower part of the furnace.

4%. Process for producing nitrids comprising the charging of the raw material into an electric shaft furnace of inverted frustoconical shape and open at the top, there heating the material by means of electric current supplied through electrodes entering from above into the charge through the free surface of the same, nitrogen or-nitrogenous gases being simultaneously introduced into the lower part of the furnace chamber, and the resulting product being removed from the furnace in an unmelted condition through openings in the lower part of the furnace.

5, Process for producing nitrids comprising the charging of the raw material an electric furnace, and there heating the same by means of electric current supplied and carried ofi through an electrode or electrodes entering into the charge in places where this has a free surface and through the lining of the furnace, nitrogen or nitrogenous, gases being simultaneously introduced into the lower part of the furnace chamber, and the resulting product being removed from the furnace in an unmelted condition through openings in the lower part of the furnace.

6. Process for producing nitrids comprising charging of the raw material into an electric furnace at the top provided with opening for introducing the charge while the furnace has such an internal form that free spaces always are formed between the brickwork of the furnace and the charge sinking down into the same through the charging opening, heating the charge by means of electric current supplied through electrodes, one or several of which enters into the charge through said free spaces, nitrogen or nitrogenous gases being simultaneously introduced into the lower part of the furnace chamber, and the resulting product being removed from the furnace in an unmelted condition through openings in the lower part of the furnace.

7. Process for producing nitrids compris- Ill ing charging of the raw material into an electric furnace at the top provided with opening for introducing the charge, while the furnace has such an internal form that free spaces always are formed between the brickwork of the furnace and the charge sinking down into the same through the charging opening, heating the charge by means of electric current supplied through electrodes, one or several of which enters into the charge through said free spaces, In witness whereof I have hereunto af nitrogen or nitrogenous gases being simulfixed my signature in presence of two wittaneously introduced into the said free nesses, spaces within the furnace chamber, the re- AXEL RUDOLF LINDBLAD. sulting product being removed from the Witnesses:

furnace in an unmel-ted condition through JnNs SOELBERG,

openings in the lower part of the furnace. ELSA H'ELLSTRiiM. 

